Original Article |
Corresponding author: Krasimir Hristov ( khristov87@gmail.com ) © 2025 Krasimir Hristov, Ralitsa Bogovska-Gigova, Nedana Georgieva.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Hristov K, Bogovska-Gigova R, Georgieva N (2025) Micro-CT assessment of sealant penetration in different types of fissures in primary molars. Folia Medica 67(1): e140934. https://doi.org/10.3897/folmed.67.e140934
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Introduction: Sealants prevent the development of dental caries by forming a protective barrier that reduces bacterial growth and food retention. The morphology of the pits and fissures and the material of the sealant can affect the depth to which it penetrates into the fissures and the longevity and durability of the sealant.
Aim: To compare the depth of penetration into fissures and pits of different types of sealants in primary molars using micro-CT assessment.
Material and methods: Forty intact primary molars were extracted just prior to their physiologic exfoliation. They were sealed with glass ionomer cement (GIC) and resin sealant. The samples were scanned with a desktop X-ray microtomograph. The fissure profile, sealant penetration depth, and depth of the unfilled part of the fissure were measured. Descriptive and inferential statistics were used to analyze the data.
Results: The median penetration depth of GIC was 89% (IQR 81.31%–100.00%) in U-type fissures and 66% (IQR 55.64%–76.77%) in V-type fissures. The deepest median penetration with resin sealant was found in U-type fissures 89% (IQR 73.16%–100.00%) and the shallowest median depth was found in IK-type fissures 34% (IQR 25.39%–41.73%). Penetration depths ranged from 34% to 43% in the I and IK fissure types. No statistically significant difference was found in the penetration of the two types of sealants in the different types of fissures (p>0.05), except for those classified as other types. There, a significantly greater depth of penetration was found in the group of teeth sealed with GIC - median 56%, compared to the resin sealant, which reached only 40% of the fissure depth (p=0.003).
Conclusion: The morphology of the fissure plays a more important role in determining the depth to which the sealant will penetrate the fissure than the type of sealant material used.
biofilm formation, implants, microbial, peri-implantitis, periodontitis
Dental caries is the most common chronic disease among children aged 5-17. [
The primary methods for preventing dental caries include the application of sealants on pits and fissures, local fluoride treatments, the use of fluoride-containing toothpaste, substituting sugar with xylitol, regular dental check-ups, and other preventive measures.[
Sealants are materials that are applied to the occlusal surfaces of molars, which are highly susceptible to dental caries.[
The first studies on pit and fissure morphology involved the use of serial sections of extracted human teeth. Based on these studies, fissures were classified into five main types based on their anatomical shape: V-shaped fissures, which are wide at the top and gradually narrowing towards the bottom; U-shaped fissures, which have almost the same width at the top and bottom; I-shaped fissures - an extremely narrow slit; IK - a narrow slit in contact with a large space at the bottom. There are also other types that do not fit into these descriptions.
The key properties of a fissure sealant material include its ability to effectively seal and penetrate deeply, while also providing strong retention and resistance to wear.[
This in vitro study aimed to compare the depth of penetration of two sealants into different fissure types in primary molars using micro-CT.
Forty intact primary molars were extracted immediately before their physiological exfoliation from healthy children aged between 9 and 11 years after signing an informed consent by the parents. The Ethics Committee of the Medical University of Sofia KENIMUS approved the study procedures (Approval No 1598/20.05.2022).
After extraction, the crowns were cleaned with hydrogen peroxide and stored in a 1% thymol solution until the study began. Prior to silanization, the occlusal surface, fissures, and pit system were cleaned using a pressurized sodium bicarbonate suspension (PROPHYflex 3, Kavo, Biberach, Germany), and rinsed with an air/water syringe to ensure no debris or contaminants hindered the sealant penetration. The crowns were then examined under an operating microscope (Semorr 3000E, Semorr Medical Tech Co., Jiangsu, China) for any occlusal carious lesions, restorations, sealants, or defects. Only intact teeth were included in the study. The teeth were randomly divided into two subgroups:
1. Group 1 (20 primary molars) – silanization with glass-ionomer cement (GIC) GC Fuji Triage Capsule white (GC Corp, Tokyo, Japan) following the manufacturer’s instructions. The enamel surface was conditioned with GC dentin conditioner for 10 seconds, rinsed for 10 seconds, and dried. The GC capsules were mixed using a GC Silvermix automatic mixer (GC Corp, Tokyo, Japan) as per the manufacturer’s instructions. A new GIC capsule was used for each sample. The cement was applied to the occlusal surface fissures using the capsule’s special cannula and spread with a brush. After allowing 10 seconds for penetration, it was light-cured for 20 seconds (Freelight 2 Elipar TM, 3MESPE, Ireland). The quality of the procedure was evaluated by a visual-tactile method and in the presence of areas with insufficient material, addition of cement was followed.
2. Group 2 (20 primary molars) – The teeth were sealed with resin sealant Grandio Seal (VOCO, Cuxhaven, Germany). The occlusal surface was etched for 20 s with 37% orthophosphoric acid 3M Scotchbond Universal Etchant (3M, Maplewood, Minnesota, USA), then carefully washed and dried with a water-air syringe. The acid treatment quality was assessed, and the occlusal surface should appear chalky white. If necessary, etching was repeated. The sealant was applied on pits and fissures using the cannula tip while avoiding incorporation of air bubbles. After waiting for 10 s to allow the material to penetrate deeper, the sealant was light cured for 20 seconds.
The examined samples were scanned with a desktop X-ray microtomograph SkyScan 1272 (Bruker, Billerica, Massachusetts, United States) in high resolution. Scanning properties were: 100 kV voltage, 100 µA beam current magnitude, 0.55 mm copper filter, conical radiation shape, and size of a single voxel 12 µm. At these parameters, the crowns were projected in their entire length into the detector field. The fissure profile, sealant penetration depth, and depth of the unfilled part of the fissure were measured using the two-dimensional images obtained. The degree of penetration was estimated with the formula:
Penetration (%)=fa/(fa+ua)×100,
where fa is the filled portion of the fissure, ua is the unfilled depth, and fa+ua is the entire fissure depth. Data were analyzed according to the type of fissure morphology (Fig.
The results were reported as median and interquartile range for numerical variables due to their non-Gaussian distribution. The distribution was assessed by using the Shapiro-Wilk test. Each two groups were compared by using Mann-Whitney U test.
Figs
There was no fissure type in which the resin sealant penetrated to full depth or close to 100%. About 84% of the fissure was filled if its profile was U-shaped and about 62% for the V-type fissures. In the remaining fissure morphologies, filling in the fissure depth was between 34 and 40%, significantly less than U- and V-type fissures (p<0.001).
Fig.
presents a comparative analysis of the penetration depth of the resin sealants Grandio Seal and GC Fuji Triage GIC capsule depending on the fissure morphology.
No statistically significant difference as found in the penetration of the two types of sealant in the different types of fissures, except for those classified as other types. In them, a significantly greater depth of penetration was found in the group of teeth sealed with GIC - 58% compared to the composite sealant, which reaches only 38% of the depth of the fissure.
Comparison of the degree of penetration by fissure profile: Grandio Seal. Different letters correspond to a statistically significant difference in the degree of penetration between the different profiles (p<0.05, Mann-Whitney U test)
The aim of this study was to compare the penetration depth of two different types of sealants used to seal primary molar fissures. Occlusal surfaces represent 6-12% of the total tooth surface but are eight times more susceptible to caries than smooth surfaces.[
The varying degree of penetration of sealants appears to be directly related to the type of fissure morphology.[
One of the materials examined in the study was Fuji Triage. It is a fluoride glass ionomer cement with a flowable consistency that provides adequate wetting and tight adhesion to tooth surfaces.[
Comparative analysis of penetration depth of Grandio Seal and GC Fuji Triage capsule against fissure morphology
Fissure type Material | V-type (Median/IQR) | U-type (Median/IQR) | I-type (Median/IQR) | IK-type (Median/IQR) | Others (Median/IQR) |
Group 1 - GC Fuji Triage | 66.59% (54.64-76.77) | 89.62% (81.31-100.00) | 45.74% (36.53-50.91) | 39.31% (35.16-41.07) | 56.58% (45.27-74.67) |
Group 2 - Grandio Seal | 59.75% (53.27-70.32) | 89.96% (73.16-100.00) | 39.38% (33.31-46.24) | 34.46% (25.39-41.73) | 40.18% (30.22-47.55) |
p (Mann-Whitney U test) | 0.197 | 0.641 | 0.203 | 0.217 | 0.003 |
The penetration of the Grandio Seal resin sealant is most likely due to the higher molecular weight of the resin and the high content of inorganic fillers (70%). The viscosity of the sealant increases with the addition of fillers to its composition, which results in improved abrasion resistance and a lower ability to penetrate the depth of fissures and pits[
The highest penetration depth was seen in U- and V-type fissures, while the lowest was in I- and IK-type. Both GIC and resin sealant showed similar results. Fissure morphology impacts penetration depth more than the type of sealing material.
This study was supported by the European Union – Next Generation EU, through the National Recovery and Resilience Plan of the Republic of Bulgaria, project No. BG-RRP-2.004-0004-C01.
The authors have declared that no competing interests exist.